This protocol evaluates the long-term safety and efficacy of infliximab, an FDA-approved drug. Infliximab was approved based on limited clinical data as a single infusion for patients with moderately to severely active Crohn's disease. This study will provide further data on re-treatment efficacy and long-term safety. It involves a maximum of 9 infusions over a 54-week treatment period, and a 3 year safety follow-up period.